The multi strand/tendons system is used in bridge and transportation structures, bonded multi strand post-tensioning systems have also been successfully applied to commercial building construction, office buildings, condominiums, hotels, parking structures, slab-on-ground foundations, ground anchors, storage tanks, stadiums, silos, and bridges.
The systems are normally adopted for bonded tendons. The tendons consist of a bundle of strand with a nominal diameter of 0.5″ (12.7 mm.) or 0.6″ (15.2 mm.).
When bonded multi strand post-tensioning systems are used for large structural members, such as beams and transfer girders, design advantages include increased span lengths and load-carrying capacity and reduced deflection. Additionally, because the strands are stressed simultaneously, less labor is required resulting in cost savings.
The strands are individually gripped in one anchor head unit and transmit their pre-stressing force by means of anchor plate casting unit. For each anchor size, special spiral reinforcement is provided at the anchor plate casting to give adequate splitting reinforcement for bustling stresses developed at the anchorage zone.
The strands in tendon are stressed simultaneously by means of a multi strand stressing jack from capacity 1,100 KN up to 5,000 KN. The strands can also be stressed individually by means of mono jack.